This invention is related to identifying multiple items with multiread transponders and, more particularly, to methods and apparatus for identifying a set of multiple items on a conveyor system using radio frequency multiread transponders.
Known radio frequency identification technology has the ability to identify multiple items simultaneously thanks to a multiread ability. A known common problem is the fact that if multiple items are placed randomly in a bag, a box or another carrier, it is necessary to read them in a three dimensional (3D) antenna. A 3D antenna is a combination of several coils placed in a 3D shape (cubic, cylindric or other shapes) generating a magnetic or electromagnetic field capable of activating transponders in any position. The shape of the antenna depends on the type of carrier which contains the items to be identified. In order for the items to be identified it is necessary that the items be surrounded by the coils of the antenna. This requires that all the items to be identified be placed inside the 3D antenna.
Very often those items are transported as a set of multiple items inside a carrier (bag, box or similar) hanging or laying on a conveyor system. In such cases it is necessary to build the antenna around the conveyor which gives several disadvantages like bigger antenna size, metal inside the antenna, motors inside the antenna.